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Electrics and loft insulation

Discussion in 'Electrics UK' started by ceres, 8 Jan 2013.

  1. ceres

    ceres

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    I'm in the process of topping up the insulation in the loft and putting in boards on loft legs for light storage. I'm lifting up the existing (approx. 100mm) insulation partly to ease it away from the eaves a couple of inches for ventilation and partly so that I can see what's underneath to draw a plan of where cables, pipes, aerials etc run for future reference - just recently moved in so it's all a big unknown. The main electric cables run over the joists in black metal conduit with circular junction boxes.

    I've only explored about half the area so far but the conduit in one place bends down towards the ceiling panel and the end is secured on the ceiling panel in what looks like a lump of cement. Two wires protrude from under the cement and these are connected into a 'lego brick'. The other side of the lego brick holds the wires from the cable that goes down through the panel a few inches away into the ceiling rose in the room below.

    I can't see any bare wire anywhere but the sheath of the cable is absent for an inch or so at both sides of the lego brick and the coloured wires are visible. This area will be boarded over. My question is should I remove insulation altogether from over this connection? Or should I wrap the lego brick and coloured wires in insulating tape? Or am I worrying about nothing and it's OK as it is?

    Many thanks in advance!
     
  2. stillp

    stillp

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    Any chance of a photo of this "lego brick"?

    Whatever it is, I wouldn't wrap it in tape, which would make a sticky mess for little if any improvement in insulation, and would impede access for inspection and/or testing.
     
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  3. ceres

    ceres

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    Thanks, yes I'll take a pic shorlty and post it.

    Sorry, just to clarify I call the white plastic connector blocks (that you join or terminate wires with) lego bricks because that's what they remind me of!
     
  4. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    The connection strip (AKA lego brick) Must be enclosed with in choc box or removed and junction box fitted, the insulation of the cores should not be visable and enclosed within choc box of junction box.
    All joints should be left accessible for inspection, testing and remedial work.
    No wrapping with insulation tape!
     
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  5. stillp

    stillp

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    I think they are more commonly called chocolate blocks or choc-blocks. They probably pre-date Lego by a few years!
     
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  6. ceres

    ceres

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    Thanks for the replies! here is the image:


    Is this what I should enclose it in:

    http://www.screwfix.com/p/chocbox/54936

    It will still be accessible - well as accessible as anything in a loft ever is! I'm using loft legs to put boards on - they'll be screwed to the loft legs so removable if needed. That was also my thought for making a plan of where cables/pipes are in relation to the joists. I tried to find a place to put the boards where there wouldn't be anything underneath but it's only a small house and there just wasn't space. I'm tidying up cable as I go, re-routing where possible and removing old stuff.

    Thank you!
     
  7. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    Yes that will do, the insulation must be within the box as shown on the screwfix link.
    The joint will need to be easily accessible, if boarding I suggest you either leave a short length of board over junction that can be lifted or a trap of some kind and mark up on the board to indicate a junction box is beneath.

    Are there any other live cables, other than that of the lights. As power cables, for sockets, showers, cookers are rated a lot closer to the demand of the circuit, than lights are and often require to be free from insulation.
    Cannot really tell what the material is at the right of connection possibly lime plaster, I would be tempted to remove that from cable.
     
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  8. ceres

    ceres

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    Thanks! I haven't worked all the way round yet but except this light, all the other cables so far are in the black metal conduit on top of the joists. The aerial cables ran over the top of the joists but I've managed to raise them all up to the rafters around the edge of the loft and removed a lot of disused aerial cables I'm sure there will be more electrical (and plumbing) in the other half of the loft which is above the kitchen/bathroom/boiler/consumer unit part of the house. While I'm not boarding that half I will still check what's under the existing insulation and tidy up whatever's needed if I can. I'll probably be back for more advice!

    I was worried about removing the mortar in case it meant the end of the conduit would be free to move around but I've just been up and checked and it's held on to the joist that it's hard up against by a bracket. So it would be better to carefully chip the mortar out?
     
  9. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    I would but isolate that circuit before you do that.
     
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  10. ceres

    ceres

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    Yes, of course, thanks! I've had a bit of a re-think about positioning the boards and I've worked out where I can place them so that the whole run between the joists on either side of the connection is kept free, with no loss of storage space. I'd rather do that than have to cut boards / construct a trapdoor etc. Sorted I think!
     
  11. sparkwright

    sparkwright

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    It looks like an attempt to reposition the light. The blob of plaster must be filling the hole in the ceiling where the light was.

    You may be able to replace this part of the wiring with a continous length (or lengths) of twin and earth cable. It doesn't have to be in conduit. However, all the conduit must maintain earth continuity.

    Replacing this section entirely with twin and earth cable will solve the problem of jointing singles in metal conduit to twin and earth cable.
    Trace where the wiring goes.
     
  12. ceres

    ceres

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    Actually, I think you might be right about the light below having been moved. It seems to me it's been moved a few inches away from the centre of the room, possibly when the previous owners installed fitted wardrobes to balance it into the centre of the remaining free ceiling area.

    The grey cable in the picture goes down through the cieling a few inches away from the connection in the picture - within the same pair of joists. The conduit runs away in a bit of a dogleg to a round 3-way conduit box about 7 feet away. I haven't properly explored where the other two arms go.

    I think I might play safe and leave the lump of mortar/plaster in place if there's a possibility it might be filling a hole. I think also that I'm not confident enough to replace the cable myself. I will though secure the connector block and wires in a chocbox as suggested.

    If I may ask another question please - I've so far found three round metal conduit boxes and they're all missing their lids so they've got dust/insulation/cobwebs etc in them. I'm assuming that's not how they're supposed to be and that I should clean them out (with the power off) and fit lids. They look to me to be imperial size - 2.5 inch external diameter and the screwholes at 2 inch centres. Do you know if there's a close metric equivalent - I've looked round a few websites and none seem to give dimensions. And the boxes and conduit are metal - would plastic lids be OK or do they need to be metal?

    Thanks for your patience!
     
  13. PrenticeBoyofDerry

    PrenticeBoyofDerry

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    Do the access boxes on the conduit runs contain joints, as they are often used for the pulling/drawing of the cables and not necessarily jointing.
    If there are connections there, debris and dust can be a fire hazard, so need removing. You can get lids from most wholesalers
    http://www.tlc-direct.co.uk/Products/COLIDG.html.
    It could be the alignment of the screw fixing that is the problem, but the lids can always be drilled for that.
    Again if joints are at these location, accessibility must be offered.
     
  14. ceres

    ceres

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    Thank you! I've only had a look at one so far and it was after dark so I couldn't switch the power off to clean it out and have a proper look but I couldn't immediately see any connections in that particular box, just the wires passing though the ports. It doesn't mean that there aren't in the other boxes though so I will check, clean them all and fit lids. I've got a Toolstation order going in today and I've added one of their plastic covers just to check for size. If it fits or can be made to, I'll order the metal ones you suggested. Looking at that link you posted - do I need the rubber gaskets too?

    Thank you again for all the replies, it's so helpful being able to check things out like this.
     
  15. ban-all-sheds

    ban-all-sheds

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    Not thought about those composite boards which lie across the joists? Probably a lot less hassle than those things on legs.
     
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